How peculiar

Look! Hubble could help uncover how “peculiar galaxies” formed

These peculiar galaxies have a lot to teach us.

ESA/Hubble & NASA, Dark Energy Survey/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA, J. Dalcanton

Space Frontiers/Archive Photos/Getty Images

There are plenty of reasons to point a high-powered telescope like Hubble into the depths of space.

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Observations of distant stars can help us understand how galaxies formed or search for signs of life outside of Earth.

Martin Marthadinata/Moment Unreleased/Getty Images

Unlike amateur astrophotographers, those operating sophisticated tools like Hubble generally aren’t capturing images for their aesthetic value — but that’s not always true.

Recently, Hubble turned its instruments to Arp 248, a group of three galaxies 200 million light-years from Earth also known as Wild’s Triplet.

The observation of Wild’s Triplet is part of an ongoing project using Hubble that’s meant to capture some of the most peculiar galaxies we know of.

ESA/Hubble & NASA, A. Riess et al.

ESA/Hubble & NASA

The galaxies surveyed may be of scientific value if observed more closely by JWST, ALMA, or Hubble itself, and they’re selected from two spectacular sources.

A Catalogue Of Southern Peculiar Galaxies And Associations and the Atlas of Peculiar Galaxies, compiled by astronomer Halton Arp, are collections of galaxies with unusual structures.

ESA/Hubble, NASA

The galaxies in the two compendiums are striking at first glance. From rings and lopsided spirals to connected galaxies like Wild’s Triplet, their shapes veer far from the familiar image of the Milky Way.

NASA, ESA, and M. Livio (STScI)

ESA/Hubble & NASA, J. Dalcanton

Cataloging these peculiar structures is worthwhile enough for showing the vast range of shapes a galaxy can take, but that’s not the only point of capturing them.

The shape of a galaxy can tell astronomers a lot about how it was formed, but deciphering that message is difficult. When Arp started his catalogs, the formation of spiral galaxies was poorly understood.

ESA/Hubble & NASA, Dark Energy Survey, J. Dalcanton

Many of the galaxies contained in Arp’s catalogs are actually interacting galaxy pairs, some of which were thought to be individual galaxies.

These catalogs provide compelling targets for future observations that could help solve the mystery of peculiar galaxies’ formation — a mission that Hubble has continued.

NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

According to the ESA, these galaxies were also chosen as targets because they’re likely to capture attention.


Using Hubble to scout targets could get us closer to understanding what causes the startling diversity of galaxies — and drive up public interest in the cosmos in the meantime.